Red Encrusting Sponge

The Red Encrusting Sponge is an odd animal scientists long thought to be a plant. Sponges are the simplest animals with multiple cells, and they take many forms. This one's name comes from its bright color ranging from red to orange-red and the fact that it's shaped like a crust, usually on stone. Around Puget Sound, look under rock overhangs at low tide to see these red splotches and feel their velvety texture.

Some sponges have branches or grow large bodies that look and feel — like sponge. But Red Encrusting sponges are just a quarter inch thick and can spread a yard across the rock where they stay attached for life. As all sponges, this one has many identical cells but no specific mouth or stomach or any specialized organs at all. Tiny waving hairs in the sponge's cells send sea water into microscopic pores. Oxygen and bits of food get filtered out; then the sponge expels water and waste through bigger holes. Get close enough and you can see these star-shaped pores.

While you're having a close look you may also notice an identically-red ½ -inch long lump on the sponge's surface. This is the Red Nudibranch, a mollusk without a shell that eats the sponge and, while eating, gets the pigment it needs for perfect red camouflage. This little creature even lays red eggs, depositing a spiral of them atop the sponge.

Red Encrusting Sponges and the many other creatures living between the tides may look durable, but they're easily damaged. When exploring their world, be sure to replace rocks just as you found them and avoid walking on seaweeds because they shelter creatures.

Purple Shore Crab

At first glance, a rocky beach on Puget Sound may seem home to few creatures, but that's far from true. Gently overturn a rock, and you'll often spot one of the beach's most abundant residents: the Purple Shore Crab. Watch closely because the lively purple shore crabs scuttle quickly away and vanish.

If you're lucky, you'll glimpse this crab long enough to see that its shell is almost square. The color in its name isn't completely accurate because the crab's body varies from olive-green to red to deep purple. Tell this species from similar ones by its hairless legs and its white-tipped claws marked with purple or red spots.

Even full-grown, these shore crabs are just 2 inches across. That's bite-sized for a gull, so until nightfall these little crabs hide under rocks where gulls can't see them. After dark, the crabs venture out to eat seaweed and bits of dead animals.

One female shore crab can lay over 36,000 eggs in a single year. The abundance of shore crabs makes them an important clean-up crew on the beach.

Purple Shore Crabs are mostly vegetarian, but be rough with them and they'll give you a good nip with that big right claw. If you do pick one up, be sure to carefully return it to its hiding place and gently replace the rock. That's home-sweet-home for this important member of the intertidal community and for many other creatures too.

Purple Sea Star

Visit a rocky beach at low tide and search for this colorful predator — the Purple Sea Star. This animal's 5 arms can measure over a foot from tip to tip. You'll find it holding tightly to rocks, but don't try to pull the star off. You'll damage the hundreds of little suction tubes it uses to move and to grip its prey.

The beautiful Purple Star is a predator. When the tide is in, the star attacks shellfish such as mussels, using those little suction tubes to pry their shells open just a crack. Then the star pushes its stomach out of its body and through this crack to digest the mussel's organs. The Purple Sea Star hunts between high and low tide where many species live. Some prey can detect the star's approach and move away. Others, fixed in place like mussels, may not last long should they settle in the sea star's realm. Through its predatory pressure, Purple Sea Stars shape the intertidal community in which they live.

Enjoy watching this beautiful creature and leave it where it is to play its important role in the ecology of Puget Sound.


All ocean animals ultimately depend on something you can't even see from a boat or dock. Enormous numbers of tiny organisms drift along near the water's surface and form the very base of the marine food chain. Some of these "plankton" are plants; others are microscopic animals.

The plants, or phytoplankton, are the absolute bottom of the food chain. Like other plants, phytoplankton photosynthesize. Combining the sun's energy, carbon dioxide and water, they make their own food and at the same time release oxygen; in fact, half the oxygen on earth.

The animal form of plankton, called zooplankton, consists of tiny animals, the larval stage of bigger ones, and some that never grow larger than the head of a pin. These tiny creatures feed mostly on phytoplankton and bacteria, but some hunt other zooplankton. They are the second important link in the marine food chain.

Together these two types of plankton form the "floating meadows" of our oceans. Small fish feed on plankton and are in turn eaten by bigger fish, sea birds, seals and whales. We also eat many of the bigger fish, such as salmon and tuna, so we too rely on plankton for food.

Pollution and global warming threaten plankton, this essential part of the environment. Let's do our part to reduce carbon dioxide and protect this ecological community, the very basis of ocean animal life. To learn easy ways to reduce your carbon footprint visit:, click on Climate Change and What You Can Do.

Pile Worm

Pile Worms are familiar to fishermen, who use them for bait. But you're unlikely to see these worms except some August evening near midnight when they spawn. Pile Worms are iridescent blue-green with red near the tail. In place of legs, many tiny paddles line their bodies, making them look a bit like giant swimming centipedes. Two impressive varieties grow over a foot long!

The Pile Worm makes itself a soft-sided tube in sand or finds a home among heavy growth on pilings and docks. Its spawning form has larger eyes, and at night by the marina lights you may see this worm swimming beautifully along. As the male releases sperm, the female worm rises from below to release her eggs. If you're very lucky, you might spot great swarms of spawning Pile Worms.

The worm's fertilized eggs form a ball of tiny, semi-transparent spheres lying below the lowest tide. Around Puget Sound these worms live maybe two years, spawn and soon die.

Our most common Pile Worm has powerful pinchers hidden in its mouth. Beware if you're a small, soft creature swimming or crawling by as these shoot out quickly to grab prey. Pile Worms prefer eating animals and will swallow a worm half their size!

As all marine creatures, Pile Worms need clean water. Puget Sound's main source of pollution is runoff from land. There are many ways you can help prevent this. For example, never pour anything down a storm drain. And landscape with native plants. They do well without fertilizer, pesticides, or watering.

Pea Crab

The Pea Crab is an unusual little parasite which you may just meet face-to-face. Pea Crabs live inside clams, mussels, and oysters, and people sitting down to a seafood meal occasionally find them. Those in the know consider them delicacies.

Pea Crabs fit their name. The largest females measure under an inch across. Full-grown males are much smaller. These tiny crabs live in the part of clams and similar creatures called the mantle, which, among other things, sifts food and oxygen from sea water. Positioned atop the mantle's gills, Pea Crabs snag bits of food, get oxygen, and enjoy the protection of their host's hard shell. Once full-grown, female Pea Crabs stay put, one per clam, oyster, or mussel. The crabs don't even develop hard shells of their own because they don't need to. The little male Pea Crabs wander, going from clam to clam. Around Puget Sound the big gaper, or horse, clams host 3 species of these little parasites. Young crabs may live in smaller bivalve species, moving to bigger ones like the gapers as they grow. Some kinds of Pea Crabs live in worm burrows or inside other types of marine creatures.

Especially for Pea Crabs living inside bivalves, "parasite" is the right label. The crab affects its host and not for the better. Besides diverting some of the clam's food, the crab damages the host's feeding apparatus as it grabs edible bits. This affects the bivalve's growth in various ways.

There are still many questions about how Pea Crabs live. They're just one more reminder of the great amount we don't know about an environment our activities affect more each day.

Pacific Squid

Just as clams, snails, and octopuses, squid are mollusks. The octopus has eight arms, and the squid does too but sports a long, cone-shaped body. The Pacific squid is the most common type of squid in Puget Sound. Because of its color, this animal is also called the "opalescent" squid, but the animal's color can change to match its surroundings or reflect its mood. A third name for this creature, "market" squid, comes from its popularity as human food.

The Pacific Squid is a skillful predator and eats small fish, crabs, shrimp, and also other mollusks, including young Pacific squid. In turn, bigger fish, birds, marine mammals, and people eat the squid.

At just a foot long, the Pacific squid is quite small, but its bigger relatives occasionally show up in Puget Sound. The Humboldt, or jumbo squid, can be almost six feet long. It used to be found only far south of Washington in warmer water. The even bigger Robust Clubhook squid has also appeared here.

All squid have several ways to avoid being eaten. They can blend into the background by almost instantly changing body color and pattern. They are jet-propelled and can zoom away suddenly, escaping enemies by expelling water from inside their bodies. And if these tricks don't work, squid eject clouds of ink to cloak themselves from view. The Pacific squid and its big relatives are definitely among Puget Sound's most amazing creatures.


Often called "killer whale," the big, black and white Orca is actually a dolphin, the world's largest, and the icon of Puget Sound. Orcas leaping and chasing salmon are a sight to remember!

Three pods, or families, of orcas live in Puget Sound, and they've captured the hearts of Washingtonians. Other orcas hunt seals, but these Puget Sound residents depend on salmon.

Researchers identify each Orca by the fin on its back and the white patch behind that fin. Every Orca has a distinct personality and is given a name: Granny, Ruffles, Oreo. This big dolphin is very social, and pod members communicate with unique calls. They also use sound pulses to navigate and to locate and catch salmon.

In each pod the oldest female is the leader. She maintains the behaviors that form the pod's particular culture. Male and female offspring stay with their mothers for life, 90 years for females and 60 for males.

People come from all over the world to see Puget Sound's Orcas. Watch them from a distance because human presence does affect Orcas. Boats getting too close, approaching too fast or making too much noise disrupts their lives. Orcas need space and quiet to find food, choose mates, raise young, socialize and rest.

Orcas depend totally on a healthy marine ecosystem. They weigh up to 8 tons, and every day each one needs hundreds of pounds of fish. As salmon decrease Orcas must swim further in search of food. Toxins washing into the ocean from the land affect their health. Let's all minimize our impact to keep water clean and protect the magnificent Orca.

Orange Sea Cucumber

Meet the amazing Orange Sea Cucumber. At first it's hard to believe that this orange blob, seen under rocks at low tide, could be amazing. The orange sea cucumber is related to sea stars but much more resembles a cucumber than any star. It's long and tapered at both ends and has spines or bumps all over.

Instead of arms for feeding like the sea star, the cucumber has tentacles. Once a tentacle is saturated with food, it's inserted into the creature's mouth, licked clean, then slowly extended back into the water.

The cucumber's skin is another of its amazing features. Made of a material called "catch collagen," the skin can change from solid to liquid and back again. The cucumber uses this feature to fit and live in crevices beneath boulders and rocks. Like the sea star the cucumber has tube feet for holding onto its home's walls. If removed from its habitat, the cucumber expels all its water, shrinking into a small, hard rock of a creature.

This animal prefers living in strong currents, where hunting is harder for its predators. When one does disturb the cucumber, it uses another amazing trick: spewing out all its guts, intestines, respiratory organs, and more. This sticky mess may entangle or distract or be a meal for the predator. While its enemy is occupied, the cucumber escapes and re-grows its organs. Cucumbers can live 5 to 10 years if they successfully avoid their main predators — sea stars, fish and humans.

The cucumber's rocky shore habitat is fragile. Life here is at risk from coastal development and pollution, including waste oil and agricultural runoff. Avoid use of chemicals around your home, and shop for or grow organic food.

Opalescent Nudibranch

The Opalescent Nudibranch ("noo-di-brank") is a beautiful mollusk without a shell. Related to snails and other animals with shells, nudibranchs are also kin to the slugs in your garden. That's why the many species of nudibranchs are sometimes called "sea slugs." On the west coast the most common of the larger ones is the Opalescent Nudibranch. Usually no more than an inch and a half long, this creature can compress to half that or stretch to double its length.

Many nudibranchs are very colorful. The Opalescent Nudibranch varies, but its body is usually yellowish-green with orange lines on top and electric blue stripes running down its sides. Many fringe-like projections cover the creature's back, each one tipped with white above an orange band. These fringes, called "cerata," take in oxygen and also contain part of the animal's digestive system.

Though they look delicate, Opalescent Nudibranchs are aggressive and will eat anything small enough for them to take on, including others of their own species. When this creature attacks an anemone (another kind of marine animal), it bites some of the tentacles that make anemones look like flowers. These tentacles have stinging cells to ward off attackers, but the nudibranch seems unaffected by them. In fact, it swallows the stinging cells which then travel through its body to end up at the tips of the nudibranch's cerata. There they become part of its own defense. It may be that the nudibranch's bright colors warn predators like fish away from the painful effects of those stingers.

When you're at the beach, look carefully into tidepools, among eelgrass blades, or even on mudflats, and you may spot this beautiful mollusk without a shell.

Olympia Oyster

The Olympia Oyster is the smallest oyster in the world and the only one native to the west coast. Once abundant from Alaska to Mexico, Olympia Oysters still inhabit that enormous range but only scattered in small numbers here and there.

A big Olympia is just 3½ inches across. Its light gray shell camouflages it in tidepools and shallow bays. As other oysters, the Olympia sucks in water and sifts out tiny plants and animals for food. Every day it filters 12 gallons, benefitting other animals and marine plants by clearing the water.

Each oyster is male or female but alternates genders during its life. Newborns soon look like tiny adults and drift until finding a hard surface to attach to for the rest of their lives. Because the preferred surface is another oyster shell, oysters can grew into huge layered colonies. These shelter many other small animals that are food for fish, crabs, and other marine creatures.

Olympia oysters taste good and grow slowly, maturing in 5 or 6 years. From the 19th century into the 20th, people harvested them more quickly than the population could replenish. And water pollution ruined oyster habitat. Companies raising oysters to sell found the Pacific oyster from Asia was bigger and faster-growing, so that's the main one farmed in the Pacific Northwest now. Work is underway to restore the native oyster, and some commercial growers raise them.

The decline of the once very common Olympia Oyster shows how important it is to follow shellfish harvest regulations and that controlling pollution is essential for the survival of all marine creatures.

Mud Snail

The Mud Snail, or Batillaria, is small and spiral-shaped. This two-inch brown and tan creature lives in huge numbers on mud-flats around certain bays in Washington, California, and British Columbia. All are near where Pacific oysters are grown.

Padilla Bay in Skagit County, Washington, is one place you can see millions of Mud Snails. At low tide, they're spread across the mud flats, plowing slowly along scraping up minute plants, called diatoms, off the surface. Watch closely and you may see some Mud Snails moving a bit more quickly. These are actually empty shells hermit crabs have taken as homes.

So why are Mud Snails only found near where Pacific oysters are grown? These are the kind oyster farmers grow and that we buy in the store. They're native to Japan rather than North America. There's a native oyster on the west coast of the U.S., the Olympia oyster, but it's quite small. Although once common, it became rare from over-harvesting. Oyster farmers began importing the much larger Pacific oysters from Japan to grow and sell here. The Mud Snail, which is native to the Asian coast and didn't occur on North American beaches, accidentally came along for the ride. It's what scientists call an "invasive species" and, typical of such creatures, has become very abundant in places. In California, the Mud Snail out-competes a similar, native snail because the Mud Snail is susceptible to fewer parasites and feeds more efficiently too.

Some invasive species cause tremendous problems for native plants and animals. You can help by thoroughly cleaning your boat and gear before moving from one body of water to another. Be sure to follow all regulations related to keeping harmful species out.

Moon Snail

A tiny round hole in an empty clam shell is a good clue the moon snail has dined. The moon snail's brown or buff-colored spiral shell, the biggest you'll find on Puget Sound beaches, can grow to 5 inches. Protruding from that shell, the snail has a huge fleshy foot on which it plows through the sand after prey.

When the moon snail senses food is near, its giant slimy foot envelops the clam or other bivalve. The snail then starts drilling into its victim's hard shell with a sharp kind of tooth called a "radula." Progress is slow, so to speed things up, the snail squirts a few drops of hydrochloric acid and enzymes to dissolve the shell and then liquefy the victim's innards. Drilling might take a few days, and the snail spends another absorbing the clam slurry inside.

Disturb a moon snail, and it will pull its big foot into its much smaller shell and clamp closed a shiny brown door called an "operculum." Moon snails have their own predators too: the sunflower star, octopuses, rock crabs, gulls, even other moon snails. Surviving these threats, a moon snail may live 14 or more years.

When it's time to reproduce in spring and summer, the female moon snail mixes more than a million tiny eggs with sand to form a leathery round collar. You may see these collars washed up on the beach waiting to break apart and develop new moon snails. Help preserve this interesting creature by tossing its egg cases back into the water.

Moon Jelly

This alien-looking animal is named for its round, translucent appearance. It is also often called Moon Jellyfish. The Moon Jelly has a circular bell, shaped like a small umbrella with eight scalloped lobes around the edge. Short tentacles hang like fringe from the lobes. Clearly visible on top of the bell are four horseshoe shaped organs, whitish with a touch of pink, purple or yellow. This common jelly can grow to 15 inches across.

Moon Jellies have, of course, never been on the moon, but in 1991 some immature Moon Jellies did go into earth orbit aboard the space shuttle Columbia. Why? Scientists wanted to know how weightlessness affects the internal organs of these young creatures.

The Moon Jelly eats plankton, which are tiny plants and animals floating near the ocean's surface. Sticky mucus covering the upper side of the bell traps the plankton. Tiny, waving hairs then move the food down the bell to the creature's mouth underneath.

These clever Jellies use the sun as a compass, guiding them in a southeasterly direction. To move they rhythmically expel water collected in the bell. This pulsing motion can't compete with strong currents or winds, and many jellies become stranded on shore. Don't touch them! Even dead, the jellies' tentacles are loaded with stinging cells that release under pressure. The stingers cause an itchy rash. Keep bare fingers and toes away!

Some fish, birds, and sea turtles eat Moon Jellies. Thousands of these animals die each year after mistaking plastic bags floating in the ocean for jellies.


At first, a low-tide mudflat seems almost lifeless. But look closer —there's lots going on. For instance, see those little piles of spaghetti-shaped sand? They mean Lugworms are living in the mud. Think of these as the earthworms of the mudflat.

Lugworms can be over 6 inches long, and to get food and hide from birds and fish, they live head-down in J-shaped burrows. Down there Lugworms avoid the drying sun at low tide and the waves of the returning water. To avoid suffocating, the Lugworm expands body segments one after another making a water current. Delicate, bushy gills along its body take oxygen from the water. The worm eats the sand and mud the current draws into its burrow. Why? Mixed with mud is the Lugworm's food: bacteria and bits of dead plants and animals. Its digestive system separates the food. Then the worm backs to the surface and ejects the inedible bits in the form of those little spaghetti piles.

A small area may have many lugworms, and they rework a lot of mud just as earthworms rework your garden soil. The burrowing and water pumping introduces oxygen that benefits other creatures. This muddy home is really full of life.

Next time you venture to the beach to dig for clams, look for those tell-tale piles. And be sure to refill your holes. Large piles of sand and mud can suffocate lugworms and other burrowing critters.

Information on this Trail Tales website was prepared under funding from the Washington State Department of Ecology’s Public Participation Grant Program. While the information was reviewed for grant consistency and accuracy of project references, this does not necessarily constitute endorsement by the Department.

Learn more about Ecology’s Anacortes Baywide Cleanup

Photo credits: Anacortes History Museum, Washington state Dept. of Ecology, Samish Indian Nation and others, as noted. Illustrations by Linda Feltner.